Re: [PATCH v1] x86/mm, asm-generic: Add IOMMU ioremap_uc() variant default
- Date: Thu, 16 Mar 2017 23:05:19 +0100
- From: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx>
- Subject: Re: [PATCH v1] x86/mm, asm-generic: Add IOMMU ioremap_uc() variant default
On Thu, Mar 16, 2017 at 03:46:51PM -0500, Bjorn Helgaas wrote:
> On Thu, Jul 9, 2015 at 7:28 PM, Luis R. Rodriguez
> <mcgrof@xxxxxxxxxxxxxxxx> wrote:
> > +/**
> > + * DOC: ioremap() and ioremap_*() variants
> > + *
> > + * If you have an IOMMU your architecture is expected to have both ioremap()
> > + * and iounmap() implemented otherwise the asm-generic helpers will provide a
> > + * direct mapping.
> > + *
> > + * There are ioremap_*() call variants, if you have no IOMMU we naturally will
> > + * default to direct mapping for all of them, you can override these defaults.
> > + * If you have an IOMMU you are highly encouraged to provide your own
> > + * ioremap variant implementation as there currently is no safe architecture
> > + * agnostic default. To avoid possible improper behaviour default asm-generic
> > + * ioremap_*() variants all return NULL when an IOMMU is available. If you've
> > + * defined your own ioremap_*() variant you must then declare your own
> > + * ioremap_*() variant as defined to itself to avoid the default NULL return.
> Are the references above to "IOMMU" typos? Should they say "MMU"
> instead, so they match the #ifdef below?
Yes. Patch welcomed.